Chronic back problems can cause pain and disability. Frequently, the cause of the back pain is due to a diseased disc located between two vertebral bodies. The disc becomes diseased or degenerated resulting in a decrease in space between the vertebral bodies, which may result in persistent pain. Surgical procedures have been developed to replace the damaged disc with an implant between the two vertebral bodies to restore the height between them. The implant can either be a fusion device, which fuses the vertebrae together or an artificial disc, which restores the motion between the vertebrae. Whether it is a fusion device or an artificial disc, surgical insertion of the implant requires preparation of the opposing bone surfaces or endplates of the vertebral bodies. The ease of use and efficiency of the instruments and procedures used to prepare and place an implant between the vertebral bodies is critical to the success of the procedure.
In the current state of the art, hand-held chisels and rasps, or powered devices, such as burrs, are used to prepare the vertebral endplate for receiving an implant. These devices are awkward and sometimes ineffective or overly aggressive in removing too much bone. In the case of powered devices, there are safety concerns when driving forces are directed towards the spinal cord or nerve roots. Typically, the conventional instruments have tips wherein the abrading element are located on the inferior and superior surfaces of the tips. The instruments are inserted between the vertebral bodies and either maneuvered by hand or power. When used manually, the surgeon pushes and pulls the instrument towards and away from him or her, cutting the endplates in an anterior-posterior direction. Often times, the instrument has to be repositioned and this motion repeated to cover the entire surface area needing to be prepared to receive the implant. Other instruments are pivoted and swept from side-to-side (like a windshield wiper) to prepare the entire surface area for the implant. This can be difficult due to the size and shape of the tip and the natural contouring of the endplate. The tip can become difficult to maneuver in the tight space. When power is used, the abrading element of the instrument moves independent of the shaft and can be overly aggressive in removing bone.
A need is present for an instrument that removes bone and cartilage in a controlled manner to prepare a bone surface for receiving an implant.